Endoscope apparatus

ABSTRACT

An endoscope apparatus of the present invention comprises an endoscope with a built-in solid state imaging device at a distal end portion of an insertion tube and a distal end optical adapter detachably connected to the distal end portion of the insertion tube of the endoscope. At least one objective optical system is provided in said distal end optical adapter and an optical image formed on said solid state imaging device through the distal end optical adapter is displayed on a TV monitor through a control device.

This application is a divisional of co-pending U.S. application Ser. No.08/515,578, filed Aug. 16, 1995.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an endoscope apparatus having a distalend optical adapter connected to an endoscope with a built-in solidstate imaging device.

2. Related Art Statement

In recent years, endoscopes which are capable of observing internalorgans in the body cavity and performing several kinds of treatmentusing treatment tools inserted into treatment tool channels as the needarises by inserting an elongated insertion tube into the body cavityhave been extensively used. These endoscopes are used not only inmedical treatment but also applied to industrial use for observing andinspecting tubes in boilers, machines and chemical plant, or an internalengine.

In the endoscopes which are used as mentioned above, an electronicendoscope is included. In the electronic endoscope, a solid stateimaging device, such as a charge coupled device (written as CCD in thefollowing) is disposed at the distal end of an insertion tube, and anendoscope image formed on the imaging device is displayed on a monitorscreen for observation.

Some of the electronic endoscopes for medical use are stereoscopicendoscopes which form an image acquired by each of two objective opticalsystems on a CCD built in an endoscope insertion tube so as to becapable of observing the image stereoscopically. The stereoscopicendoscopes are indicated in Japanese Patent Application Laid Open No.64-26813/1989 and U.S. Pat. No. 5,122,650.

Further, in Japanese Patent Application Laid Open No. H1-197716/1989,two objective optical systems having different magnification aredisposed and an image obtained by each objective optical system isformed on a CCD corresponding to each optical system, so that anendoscope for, what is called as telephotographic/wide which can observetwo images including an ordinary observation image and a magnified imageis shown.

On the other hand, in an electronic endoscope for industrial use, adistal end optical adapter type has been known in the art. In the distalend optical adapter, various kinds of objective optical systems forvarious uses have been arranged.

Further, in endoscopes used in the industrial field, some endoscope hasa zooming function provided in an objective optical system and afunction being capable of manually switching between a direct sight anda side sight, what is called as a pan viewing function has been highlyrequired.

When a mechanism for performing a pan viewing function is provided atthe distal end of the endoscope for industrial use, not only theendoscope distal end diameter becomes thick but also the structure iscomplicated. That has become a factor of increasing expenses.

The endoscopes which can perform stereoscopic vision observation shownin Patent Application Laid Open No. 64-26813/1989 and U.S. Pat. No.5,122,650, and the endoscopes which can perform telephotographic/wideoperation shown in Japanese Patent Application Laid Open No.H1-197716/1989 are exclusively used for stereoscopic vision observationor telephotographic/wide operation.

In addition, because the endoscopes form images acquired by twoobjective optical systems ordinarily use a pair of optical systems forstereoscopic vision observation, the two optical systems have the samef-number (brightness/stop value) and send the common illumination lightto both optical systems. In other words, it was not necessary to adjustthe quantity of illumination light for each optical system from a lightsource through a light guide. However, as mentioned above, if anobservation image obtained by each objective optical system is formed onthe CCD corresponding to each objective optical system and the commonquantity of light illuminates two objective optical systems havingdifferent magnification in an endoscope performing telephotographic/wideoperation by using the common quantity of light, an image having properbrightness for each optical system cannot be obtained, so that it wasnecessary to adjust and supply the quantity of illumination light beingappropriate for each optical system.

OBJECT AND SUMMARY OF THE INVENTION

An object of the present invention is to provide an endoscope apparatusin which stereoscopic vision observation or two kinds of imageobservation, such as telephotographic/wide observation or a functionincluding pan viewing is easily formed in addition to ordinaryobservation in an endoscope having a solid state imaging device.

Another object of the present invention is to provide an endoscopeapparatus in which observation can be carried out in appropriatebrightness when an image is observed using a function of stereoscopicvision or two kinds of telephotographic/wide images or pan viewing in anendoscope having a solid state imaging device.

In short, the endoscope apparatus of this invention comprises anendoscope with a built-in solid state imaging device at the distal endof the insertion tube, and a distal end optical adapter detachablyconnected to a distal end portion of the insertion tube of theendoscope, wherein at least one objective optical system is provided inthe distal end optical adapter and an optical image formed on a solidstate imaging device through the distal end optical adapter is displayedon a TV monitor through a control device.

The other characteristics and advantages of this invention will besufficiently apparent in the following explanation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 9 relate to a first embodiment of the present invention;

FIG. 1 is an illustration showing a conceptual construction of anendoscope apparatus;

FIG. 2 is a sectional view of a configuration of an distal end opticaladapter formed of an objective optical system;

FIG. 3 is a front view of the distal end optical adapter in FIG. 2;

FIG. 4 is a sectional view of a configuration of a distal end opticaladapter formed of two objective optical systems and an endoscope distalend portion;

FIG. 5 is a front view of the distal end optical adapter in FIG. 4;

FIG. 6 is a sectional view showing another configuration of a distal endoptical adapter formed of two objective optical systems;

FIG. 7 is a sectional view of I--I in FIG. 6;

FIG. 8 is a sectional view of another configuration of a distal endoptical adapter formed of two objective optical systems;

FIG. 9 is a block diagram of an example of a configuration of a controldevice;

FIG. 10 is a conceptual construction of an endoscope apparatus in whichanother configuration of a distal end adapter is connected to anendoscope distal end;

FIG. 11 is a sectional view explaining a second embodiment of anendoscope connectable to a distal end optical adapter; and

FIG. 12 is a sectional view showing a configuration of a distal endoptical adapter in which gravity direction detecting means is disposed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 9, a first embodiment of the present inventionwill be explained.

As shown in FIG. 1, an endoscope apparatus 1 is formed of an endoscope2, a light source 3 supplying illumination light to a light guide cable(not shown) built in the endoscope 2 a control device 4 driving andcontrolling a charge coupled device (CCD in the following) (statedlater) built in the endoscope 2 and converting an electric signal of anoptical image formed on a CCD and photoelectrically converted into apicture signal, and a TV monitor 5 displaying the picture signal of theoptical image converted by the control device 4.

The endoscope 2 is formed of a distal end portion 21 to which a distalend optical adapter 30 stated later can be detachably connected andcontaining a built-in CCD, an insertion tube 24 consisting of anelongated and flexible bend portion 22 and soft portion 23, an operationportion 25 positioned on the proximal end of the insertion tube 24 andheld by an operator, a universal cord 26, which is extended from theoperation portion 25, containing a built-in light guide cable and signalcable, and a connector 27 provided at the end of the universal cord 26.

In the connector 27, a light guide connector 28 connected to the lightsource 3 is provided. Through the light guide connector 28, illuminationlight is transferred to the distal end portion of the endoscopeinsertion tube 24. Also, in the connector 27, an EL connector 29 havingan electric contact for being connected to the control device 4 isprovided. An electric signal of the optical image photoelectricallyconverted by a CCD disposed at the distal end portion 21 of theendoscope insertion tube 24 is led to the control device 4 through asignal cable.

Further, the light source 3, the control device 4, and the TV monitor 5which are connected to the endoscope 2 are not separated as shown inFIG. 1 and can be formed as a unit as the occasion demands.

The configuration of the distal end optical adapter which is detachablewith regard to the endoscope distal end portion 21 will be explained inreference to the drawings.

FIGS. 2 and 3 are examples of a distal end optical adapter 30A which isdetachable with regard to the endoscope distal end portion 21. In theendoscope distal end portion 21, an image pickup unit 44 in whichelectric components including a CCD 41 and an IC 42 and a signal cable43 are sealed from a CCD back surface to a cable connecting portion as aunit with adhesive to be molded and a light guide 45 are arranged. Thelight guide 45 is branched into two portions at the distal end of theendoscope distal end portion and follows two illumination opticalsystems 33 and 33 provided in the distal end optical adapter 30A asshown in FIG. 3. On the outer peripheral surface of the endoscopedistalend portion 21, a screw for attaching and detaching an adapter 46 isfixed. Reference numeral 47 is a locational groove locating the opticalsystem of the distal end optical adapter 30 so that the optical systemof the distal end optical adapter 30 faces the optical system of theendoscope 2.

A distal end optical adapter 30A shown in FIGS. 2 and 3 used forordinary observation has an objective optical system 31 in such a waythat an optical image is formed on the CCD 41 built in the endoscopedistal end portion 21. While the objective optical systems 31 and twoillumination optical systems 33 and 33 are provided in a rigid portion32 of the distal end optical adapter 30A, a screw portion 34 is formedon the proximal end inner peripheral surface of the rigid portion 32 asconnecting means for being detachably connected to the endoscope distalend portion 21. Also, reference numeral 35 is a locational pin disposedin the locational groove 47.

The distal end optical adapter 30A and the endoscope distal end portion21 are connected as a unit by spirally fitting the screw for attachingand detaching an adapter 46 provided on the outer peripheral surface ofthe endoscope distal end 21 and the screw portion 34 formed on the innerperipheral surface of the distal end optical adapter 30A. At this time,by disposing the locational pin 35 in the locational groove 47, thecenter of the optical axis of the CCD 41 coincides with the center ofthe optical axis of an objective optical system 31, so that an ordinaryendoscope image is obtained and the endoscope 2 performing endoscopeobservation is formed.

Referring to FIGS. 4 and 5, the distal end optical adapter 30 beingdetachable with regard to the endoscope distal end portion 21.

A distal end optical adapter 30B shown in the drawings is provided withtwo objective optical systems 36 and 37 in order to form two opticalimages on the CCD 41 built in the endoscope distal end portion 21. Inthe rigid portion 32 of the distal end optical adapter 30B, theobjective optical systems 36 and 37 and the two illumination opticalsystems 33 and 33 are disposed.

The objective optical systems 36 and 37 can be two objective opticalsystems having the same function or different functions.

First, the two objective optical systems 36 and 37 having differentfunctions will be explained.

The objective optical systems 36 and 37 provided in the distal endoptical adapter 30B shown in the drawings are, for example, different indepth of observation and brightness. That is to say, the objectiveoptical system 36 is formed to focus a near point and to stop down thediaphragm, and the objective optical system 37 is formed to focus a farpoint and to open the diaphragm. Therefore, by means of connecting thedistal end optical adapter 30B to the endoscope distal end portion 21, anear point of a subject can be observed using the objective opticalsystem 36 and a far point of a subject can be observed using theobjective optical system 37. The endoscope being capable of observing anear point to a far point can be formed by connecting the distal endoptical adapter 30B. The distal end optical adapter 308 is not limitedto the one having different depth of observation and brightness and, forexample, can be the one having different angles of view. In this case,the angle of view of the objective optical system 36 is specified to anarrow telephotographic angle in which, for example, 30° is set and theangle of view of the objective optical system 37 is specified to a wideangle in which, for example, 120° is set. The other configurations arethe same as the configurations of the distal end optical adapter in thefirst embodiment. The same reference numbers are given to the samemembers and the explanation is omitted.

Accordingly, when observation is performed in the endoscope in which thedistal end optical adapter 30B is connected to the endoscope distal endportion 21, first of all, a part we want to magnify in detail andobserve can be observed in telephotographic/wide ways as using a zoomlens in the objective optical system 36 after an image in a wide rangepicked up by the objective optical system 37. At this time, by makingillumination lenses disposed in the illumination optical systems 33 and33 correspond to respective objective optical systems 36 and 37 to formthe illumination lenses for a narrow angle and a wide angle, so thatmore effective observation can be conducted using the objective opticalsystems 36 and 37. Further, the objective optical system 36 for thenarrow angle can be used for observing a turbine and the objectiveoptical system 37 for the wide angle can be used for observing a pipe.

As shown in FIGS. 6 and 7, a distal end optical adapter 30C can beformed by combining a visual field direction of an objective opticalsystem and an illumination optical system with a visual field directionof the other objective optical system and the other illumination opticalsystem in different ways.

As shown in the drawings, the distal end optical adapter 30C is a directsight type in which an observation plane of an objective optical system38 faces the direction of an insertion tube of an endoscope and is aside sight type in which the other observation plane of an objectiveoptical system 39 faces the perpendicular direction to the axis of theendoscope. In accordance with the specification of the objective opticalsystems 38 and 39, an endoscope which can observe both directions of adirect sight type and a side sight type can be formed. The otherconfigurations are the same as the configurations of the aforesaiddistal end optical adapter 30B. The same reference numerals are given tothe same members and the explanation is omitted.

By connecting the distal end optical adapter 30C to the endoscope distalend portion 21, a subject positioned on the front surface of theendoscope distal end portion is observed by using the direct sight typeobjective optical system 38 and a subject positioned on the side surfaceof the endoscope distal end portion is observed by using the side sighttype objective optical system 39, so that a subject can be observed asif a pan viewing function of the both directions of the direct sight andside sight is provided.

Additionally, a distal end optical adapter 30D shown in FIG. 8 forms aninclined sight type in which objective optical systems 40A and 40B facedifferent directions. In this case, two illumination optical systems 33and 33 are provided in the objective optical systems 40A and 40B,respectively, for illuminating each direction corresponding to theobjective optical systems 40A and 40B. The other configurations are thesame as the configurations of the aforesaid distal end optical adaptershown in the first embodiment. The same reference numerals are given tothe same members and the explanation is omitted.

By connecting the distal end optical adapter 30D to the endoscope distalend portion 21, an endoscope which can observe a subject by using thetwo objective optical systems 40A and 40B facing different inclineddirections with regard to the endoscope distal end portion and obtainingan extensive range of images is formed. Needless to say, it can beformed not only to make both objective optical systems inclined sighttypes but also to make only an objective optical system an inclinedsight type and to make the other a direct or a side sight type.

Further, as explained above, when the plurality of objective opticalsystems including the distal end optical adapter 30B formed by combiningobjective optical systems having different depth of observation andbrightness, the distal end optical adapter 30C formed by combiningobjective optical systems having different directions of visual fields,and the distal end objective optical adapter formed by combiningobjective optical systems having different angles of view are providedand an optical image Is formed on a CCD through the plurality ofobjective optical systems, an observed image of appropriate brightnesscannot be obtained because, if the same quantity of illumination lightis emanated from a light guide arranged so as to correspond to eachobjective optical system by making the endoscope distal end portionbranch at the distal end, there is difference in f-numbers of theobjective optical systems between an observed image acquired by anobjective optical system and an observed image acquired by the otherobjective optical system. Thus, it is necessary to cause the brightnessof each observed image acquired by a plurality of optical images formedon a CCD through a plurality of objective optical systems to beappropriate brightness.

Then, as shown in FIG. 9, a CDS circuit 51 for picking out a signalbeing the basis of a video signal, a screen changing circuit 52 forchanging an image pickup surface of the CCD 41 to a right half, a lefthalf or an ordinary whole screen, a video signal processing circuit 53for generating a reference TV signal, a light intensively adjustingcircuit 54 for supplying a control signal controlling the quantity ofillumination light fed to the light guide connector 28 from the lightsource 3 to obtain an observed image of appropriate brightness and ascreen selector 55 for controlling the screen changing circuit 52 aredisposed and the control device 4 is formed by connecting a changeoverswitch 56 provided on a panel surface of the control device 4 to ascreen selector 55. A light quantity control system 50 for obtaining twoobserved images having proper brightness by using a CCD is formed of theCDS circuit 51 of the control device 4, the screen changing circuit 52,the light intensity adjusting circuit 54, the screen selector 55 and achangeover switch 56.

In other words, when the brightness of one of the observed imagesobtained by two optical images formed on a CCD is inappropriate, animage formed on a right or left half of the image pickup surface of theCCD 41 is selected by operating the changeover switch 56. Then, a pixelnumber in the horizontal direction of the CCD 41 is counted in thescreen selector 55 based on a control signal selected by the changeoverswitch 56. A signal for displaying only a right or left half of theimage pickup surface is sent to the screen changing circuit 52. Then, inthe screen changing circuit 52, a final screen changeover operation isperformed.

After that, an electric signal in which an optical image formed of theimage pickup surface of the CCD 41 selected by means of the screenchanging circuit 52 is photoelectrically converted, and sent to thelight intensity adjusting circuit 54. In the light intensity adjustingcircuit 54, in order to adjust the quantity of the illumination lightemanated from the light source 3 based on luminance information of anelectric signal of the optical image transmitted from the image pickupsurface of the selected CCD 41, for example, a control signal fordriving a diaphragm blade (not shown) provided in the light source 3 isgenerated. Further, the diaphragm blade is adjusted by outputting thecontrol signal generated by the light intensity adjusting circuit 54.Thus, proper quantity of illumination light is supplied to theillumination optical system corresponding to each objective opticalsystem arranged in the distal end optical adapter from the light source3 through the endoscope 2.

In this way, the quantity of illumination light emanated from theillumination optical system of the distal end optical adapter toward anobject is properly adjusted to the brightness in accordance with eachobjective optical system, so that two observed images having properbrightness can be acquired using a CCD.

Next, the two objective optical systems having the same function will beexplained.

In the case of a distal end optical adapter 30E in which the twoobjective optical systems 36 and 37 disposed in approximately the distalend optical adapter having similar configuration shown in FIG. 4 havethe same function, a screen changing device 6 is provided in theendoscope apparatus 1 supplied with the endoscope 2 to which the distalend optical adapter 30E is connected as shown in FIG. 10.

Therefore, by connecting the distal end optical adapter 30E to anendoscope distal end portion 21, a video signal of a subject imaged in adifferent position in a CCD is transmitted to a picture image changingdevice 6 through the objective optical systems 36 and 37. Then, anendoscope which is capable of obtaining a stereoscopic image of anexamined part is acquired by displaying the video signal of a subjecttaken by the objective optical systems 36 and 37 is displayed on the TVmonitor 5 alternately through an A/D converter 61, a memory 62, apicture image changing circuit 63, and a D/A converter 64.

In this manner, endoscope apparatuses dealing with ordinary endoscopeobservation, telephotographic/wide observation, pan viewing observationand a stereoscopic vision observation can be easily constructed bymaking a detachable distal end optical adapter at the endoscope distalend portion consist of an objective optical system, an apparatus becapable of observing a near point to a far point by providing twoobjective optical systems, an apparatus be capable of performingtelephotographic/wide observation using a wide-range picture image and amagnified image in detail, an apparatus be capable of observing bothdirect sight and side sight in such a way that a pan viewing function isprovided, and further two functions of objective optical system be thesame by exchanging adapters.

Also, in an endoscope with a built-in solid state imaging device, sincean endoscope apparatus is formed of a control device and a picturechanging device, simultaneous observation including stereoscopic visionobservation and a direct sight/side sight observation and a simultaneousobservation including wide/telephotographic observation can beinexpensively constructed in addition to ordinary observation withoutchanging the formation of the aforesaid endoscope apparatus.

Also, the picture image changing device 6 is disposed between thecontrol device 4 of the endoscope apparatus formed of the endoscope inwhich a distal end optical adapter with an objective optical systemsdisposed having different functions is connected to the endoscope distalend portion as mentioned above and the TV monitor 5, or is made to bethe control device 4 having the screen changing circuit 52 shown in FIG.9, the screen selector 55 and the changeover switch 56, so that not onlystereoscopic vision observation can be easily performed but also onlyone of the picture images picked up by the objective optical system canbe displayed or both pictures can be alternately displayed on the TVmonitor 5. Additionally, pictures picked up by the objective opticalsystem are switched and displayed by changing an exterior switch as theoccasion demands, or an observation picture image can be more easilyseen and an examination efficiency can be improved by selecting adesired one and displaying it at the center on the TV monitor 5.Further, instead of arranging a picture image changing device betweenthe control device 4 and the TV monitor 5, needless to say, the controldevice 4 may have the function of the picture image changing device 6.When an image is formed on a CCD through two objective optical systemsas stated above, in comparison with obtaining an image on a CCD,generation of flare is concerned. Therefore, it is desirable to coat CCDcover glass with coating for preventing flare. In addition, it isexplained that a plurality of objective optical systems are twoobjective optical systems in the aforesaid embodiment; however, thenumber of objective optical systems can be three or more.

Next, a second embodiment of a light guide inserted into an endoscopewill be explained by referring to FIG. 11.

As explained above, when an observation picture image is acquired byforming a plurality of optical images on a CCD by providing a pluralityof objective optical systems including the distal end optical adapter30B in which objective optical systems having different depth ofobservation and different brightness are combined, and the distal endoptical adapter 30C in which objective optical systems having differentdirections of visual field are combined, a distal end optical adapter inwhich objective optical systems having different angles of view arecombined, if the same quantity of illumination light is emanated from alight guide which is branched into two ends and disposed at the distalend of an endoscope distal end portion in accordance with each objectiveoptical system, an observation picture image of appropriate brightnesscannot be obtained because the difference is produced according todifferent f-number of each objective optical system between anobservation picture image acquired by an objective optical system and anobservation picture image acquired by another objective optical system.

For this reason, in this embodiment, an endoscope 70 is constructed asfollows to make the brightness of each observation picture imageobtained by a plurality of optical images formed on a CCD through aplurality of objective optical systems.

As shown in FIG. 11, in the endoscope 70 of this embodiment, a firstlight guide 71 and a second light guide 72 are arranged in oppositepositions to which, for example, two illumination optical systems areprovided in the distal end optical adapter which can be detachablyconnected to the distal end portion of the endoscope 70, respectively.

That is to say, the first light guide 71 corresponding to a firstobjective optical system 73 facing the objective optical system 36 ofthe distal end optical adapter 30B shown in FIG. 4 and the second lightguide 72 corresponding to a second objective optical system 74 facingthe, objective optical system 37 of the distal end optical adapter 30Bare provided. Reference numeral 71a is a first illumination lens of thefirst light guide 71, and 72a is a second illumination lens of thesecond light guide 72. The other configuration of the endoscope 70 isthe same as that of the endoscope 2. Thus, the same reference numeralsare give to the same members and the explanation is omitted.

The first light guide 71 and the second light guide 72 are connected toa light source 3a through light guide connectors 28a and 28b provided ona connector 27a. In the light source 3a, while a first diaphragm device75a for supplying illumination light to the first light guide 71, afirst diaphragm driving portion 76a, and a first lamp 77a are provided,a second diaphragm device 75b for supplying illumination light to thesecond light guide 72, a second diaphragm driving portion 76b, and asecond lamp 77b are provided.

When an endoscope apparatus 1 provided with the endoscope 70 constructedas mentioned above and the light source 3a observes an object, theobject illuminated by the illumination light transmitted in the firstlight guide 71 and emanated from the illumination optical system of thedistal end optical adapter forms an optical image on, for example, aright half of a CCD 41. The electric signal of an optical imagephotoelectrically converted by the CCD 41 and is transmitted to acontrol device 4. Similarly the object illuminated by the illuminationlight transmitted in the second light guide 72 and emanated from theillumination optical system of the distal end optical adapter forms anoptical image on, for example, a left half of the CCD 41. The electricsignal of the optical image photoelectrically converted in the CCD 41 istransmitted to the control device 4.

In a control device 4 to which the electric signal of these opticalimages are transmitted, a control signal for driving a first diaphragmdriving portion 76a for controlling the first diaphragm device 75a foradjusting the quantity of illumination light emanated from the lightsource 3a to the object or tile second diaphragm driving portion 76b forcontrolling the second diaphragm device 75b is produced.

Then, a control signal for driving the first diaphragm driving portion76a or the second diaphragm driving portion 76b and being produced inthe control device 4 is fed to the light source 3a to properly adjust,for example, a diaphragm blade which forms the first diaphragm device75a or the second diaphragm device 75b equipped in the light source, sothat appropriate brightness of each of a plurality of observationpicture images obtained by means of a CCD are adjusted.

In this way, light guides are disposed by making the light guidescorrespond to a plurality of objective optical systems arranged in anendoscope. The quantity of illumination light emanated toward an objectthrough a light guide and illumination optical systems can beappropriately adjusted by making the quantity of illumination lightcorrespond to the brightness of the observation picture image based onan electric signal obtained from an optical image formed through eachobjective optical system. Accordingly, it is possible to cause thebrightness of a plurality of observation picture images formed on a CCDto make the brightness of a plurality of observation images formed on aCCD coincide with appropriate brightness and observe the picture images.

In the meantime, there is an observation optical system of an endoscopein which a steel ball for direction showing a gravity direction of anobservation picture image. When observation was performed using theendoscope, it was found that nonconformity in which observation wasdifficult to be conducted because images of the steel ball for directionwere overlapped in an observation picture image. Therefore, as shown inFIG. 12, a minute steel ball for direction 83 is disposed in anobjective optical system 82 from the two objective optical systems 81and 82 as gravity direction detecting means for detecting the gravitydirection. Accordingly, because an observation picture image is obtainedin the objective optical system 81 and the gravity direction of theobjective optical system 82 can be found, an observation picture imagecan be easily seen.

It is not necessary that the objective optical system 82 containing asteel ball for direction indicating the gravity direction has formingimage performance especially. The objective optical system can besandwiched between transparent parallel planes. Additionally, anobservation picture image easily observed can be obtained by making apicture for the gravity direction smaller than a picture forobservation.

In this invention, it is apparent that working modes different in a widerange can be formed on the basis of this invention without departingfrom the spirit and scope of this invention. The invention is notrestricted by its specific working modes except as limited by theappended claims.

What is claimed is:
 1. An endoscope apparatus, comprising:a distal endportion of an insertion tube of an endoscope adaptably fitting differenttypes of distal end optical adapters, each of the distal end opticaladapters having an objective optical system providing at least two kindsof image observation; a light quantity control system controlling aquantity of illumination light emanating from a light source to theobjective optical system in each of the distal end optical adapters toprovide respective brightness for optical images generated for the atleast two kinds of image observation by the objective optical system ofeach of the distal end optical adapters; and an image selecting circuitselecting one of the optical images generated for the at least two kindsof image observation, wherein the light quantity control system controlsthe quantity of the illumination light depending on the selected one ofthe optical images generated for the at least two kinds of imageobservation.
 2. An endoscope apparatus as recited in claim 1, whereinthe light quantity control system comprisesa light intensity adjustmentcircuit adjusting the quantity of illumination light from the lightsource based on luminance information from a photoelectrically convertedsignal of the selected one of the optical images from the imageselecting circuit.
 3. An endoscope apparatus, comprising:a distal endportion of an insertion tube of an endoscope adaptably fitting differenttypes of distal end optical adapters, each of the distal end opticaladapters having an objective optical system providing at least two kindsof image observation and a plurality of light guides; a light quantitycontrol system controlling a quantity of illumination light emanatingfrom a light source for the plurality of light guides to providerespective brightness for optical images generated for the at least twokinds of image observation by the objective optical system of each ofthe distal end optical adapters; and an image selecting circuitselecting one of the optical images generated for the at least two kindsof image observation, wherein the light quantity control system controlsthe quantity of the illumination light depending on the selected one ofthe optical images generated for the at least two kinds of imageobservation.
 4. An endoscope apparatus as recited in claim 3, whereinthe light quantity control system comprisesa light intensity adjustmentcircuit individually adjusting the quantity of illumination light fromthe light source for one of the plurality of light guides based onluminance information from a photoelectrically converted signal of theselected one of the optical images from the image selecting circuit. 5.An endoscope apparatus, comprising:a distal end portion of an insertiontube of an endoscope adaptably fitting different types of distal endoptical adapters, each of the distal end optical adapters having aplurality of objective optical systems providing at least two kinds ofimage observation and a plurality of light guides, each of the pluralityof light guides corresponding to each of the plurality of objectiveoptical systems; and a light quantity control system controlling aquantity of illumination light emanating from a light source for theplurality of light guides to provide respective brightness for opticalimages generated for the at least two kinds of image observation by theplurality of objective optical systems of each of the distal end opticaladapters; and an image selecting circuit selecting one of the opticalimages generated for the at least two kinds of image observation,wherein the light quantity control system controls the quantity of theillumination light depending on the selected one of the optical imagesgenerated for the at least two kinds of image observation.
 6. Anendoscope apparatus as recited in claim 5, wherein the light quantitycontrol system comprisesa light intensity adjustment circuitindividually adjusting the quantity of illumination light from the lightsource for one of the plurality of light guides corresponding to one ofthe plurality of objective optical systems which generated the selectedone of the optical images based on luminance information from aphotoelectrically converted signal of the selected one of the opticalimages.